Homemade Simple Metal Detector ----- Simple Homemade Metal Detector

Homemade Simple Metal Detector, Simple Homemade Metal Detector Keywords: homemade simple metal detector Homemade simple metal detector The working principle of this circuit is such that the oscillator of the L oscillator also changes when the inductance amount of the inductor coil is changed. Any metal body is changed from this detection inductor. How to change the frequency depending on the working frequency of the metal characteristics and the circuit. If the operating frequency is high, the metal can be considered a short circuit ring, which will reduce the inductance of the inductor, so that the operating frequency of the oscillator is increased; if the operating frequency of the oscillator is sufficient to ignore the vortex loss, this detection It is possible to distinguish black metal or colorless metal. It is difficult to make a oscillator coil that is not higher than the 200 Hz oscillator. Therefore, the oscillating circuit oscillation work frequency selects about 300 kHz, so that the inductor is easy to make, just use a coaxial cable according to the size Conducted around the top. The circuit includes an oscillator T1, a frequency-voltage converter IC1 and a MOS dual actuator IC2. The value of the probe of the head coil is 440 mm, the value of C1 and C2 ensures that the frequency of the oscillator is approximately 300 kHz. If a smaller diameter detecting ring is used, the coil needs to be more turns. The oscillator signal level must reach at least 500MVPP so that the 4046 integrated block can be driven well, at this level, the phase comparator ensures that the phase-locked loop inside the integrated block is always locked. The source follower output on 10 feet is then sent to the IC2 CA3130 for a large amplitude amplification. The center frequency of the phase-locked loop is also the zero point of the micro-moon table at the center is adjusted by the potentiometer P1. If the sensitivity of the opuer is extremely high, it is necessary to use P2 carefully. The native sensitivity is adjusted by P3, which is connected to the negative feedback loop and the inverting input of IC2; and there is also a non-inverting input through the microam and R10 to IC2. Of course, different impedances can be used, but the values ​​of R9, R10 and R11 can be used. Note: When detecting metals, the size of the detectors is a certain relationship between the detection coil. It is necessary to use a 440mm (17.5-inch) diameter detection coil to detect a coin size.

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